Telephone system.



, R. '11. MANSON.

TELEPHONE" SYSTEM.

V APPLIGATIOB FILED APR. 18, 1907.

Patented Apr. 20, 1909.

5NPTIEI) STATES SIGNOR TO THE DEAN ELECTRIC COMPANY, OF ELYRIA, 01110, A CORPORATION OF OHIO.

:JANSON, F ELYllIA. OHIO, AS

rnirnn'r onnion;

TELEPHONE SYSTEM.

zen of the United mare-s; nisidi'hg at Elyria,

in the county of Lorain and State of Ohio, have invented certain new and useful Improvcrnents in Telephone Systems, of which the following is a specification, reference being had therein to the accompanying draw- My invention relates to tele hone systems, and has reference to the sigma ing means en1- loyec therein and the circuit connections therefor.

The invention (Olnprlsrfi means for preventing a subscriber on a magneto line from ringing through the cord circuit at the exchange and operating the hell or bells on a connected line circuit. My circuits have the additional advantage of making it possible to ring down the clearing out dro from one line when the other connected ine circuit has a short circuit existing between its two sides, or when it has air-extremely low resistance piece of apparatus connected across the same.

In so-called magneto telephone systems,

wherein the signaling currents-are generated by hand machines worked by the bscribers, it is customary to bridge a high wound nnnunciator magnet across each connecting cord circuit, so that at the conclusion of a conversation the subscrihersmayring oil and by aetuating'lhe bridge annunciator apprise the operator of their desire for disconnection. lhe brid ed clearing out drop being high wound, a ow resistance bridge across any part of the connected circuits will obviously take up aproportionately ls-rge part of theringing current, and if this bridge happens to be composed of one. or more ringing branches, the result will he that one or more of the ringers will be actuated, while the high resistance hridge through the clearing out onnunciator may not receive current enough to signal the central ollice operator for disc onnection.

Subsidiary objects and advantages will appear from the following detail description taken in connection with the accompanying drawings.

My invention is illu trated in thc accompanying drawings in ohiwh Figure l is a diagram showing a four-party hmtcrminut'uig in n swuchbmu-d ack in the Specification of Letters Patent.

Application filed A r: 18,

1907. Serial No. 869,014.

central oliice with a connecting cord circuit having my present invention applied thereto. Fig. 2 is a diagram of 9. modified form of cord circuit: also embodying the invention, and

show the effect of a shunt or short circuit on the ringing current.

Referring to the drawings, i2 is It sub scribers line extending irom the central offlee to four substations, at each of which ere located a hand generator G, a rin er Q, a receiver R, transmitter T, a switch liook H, and an induction coil I, the transmitter being supplied by a local battery b. The genera tor and ringer are in bridges across the line, both normally closed at the switch hook H, but the generator branch normally'open at contacts governed in its operation. Both the generator and ringer are referabl cut oil' when the receiver is taken r0111- the 100k, although this is not essential, provided the ringers are wound sufliciently riugerslin the resent case are supposed to be tuned and otherwise adjusted so that each one will-respond to a particular fre? uenoy of ringing current only. At the centre oflice I provide four common generators G, G, G and .G which roduce currents of proper fre rencies to se ectively actuate the four bell s on each line. Such an arrangement is known as a harmonic system and is selected for illustration herein because without my present invention the current employed in ringing off is liable 'to actuate the low freuency ringers of such a harmonic system.

The line 1-2 is shown terminating in the switchboard jack J associated with which I provide the usual line annunciator A, which is.cut oil in the jack upon the insertion of a plug P or P. For the sake of simplicity in the diagram, l have shown portions of another subscriber's line at 3-4,

annuncmtor A. This line also has a generator :at the substation which I have marked G", and which is employed for actnrting both the line annunciotor A and the clearlug nut nnnunciator A. This clearing out annuncintor is bridged acros the cord con-,- duetors which connect the plugs P and l. The conductor which connects the tips of g the plugs is marked 56, and the conductor 1 connectingthe sleeves of the plugs is marked l 7-R, each conductor being divided min lwo Patented April 20, 1909. V

Fig. 3 is a' simplified diagram intended to.

terminating in a jack J and having a line high. The

portions by condensers C'-C for a purpose to be described. In order that the 0 erator may communicate with the subscri )ers, l provide a telephone set 0, which is adapted tobe connected across the conductors 5 set of selective keys 1:, k is" and It", controlling the connection of the four selective generators to the key K.

The annunciator A is bridgcd across the cord circuit by means of conductors 9--l0 and the gist of my intention lies in the manner in which this bridging is done. The conductor 0 is connected to the conductor 5 on the left hand side of the condenser C (see Fig. 1), while the conductor 10 is connected to the conductor 8 at the right hand side of its condenser C. The use of these condensers in a magneto cord circuit is one of the distinguishing features of my invention, and the cross connection of the drop A from one side of one condenser to the other side of the other condenser is another distinguishing feature. This drop is of very high impedance preferably wound to 500 ohms resistance and its connection across the cord circuits does not seem to -u nbalance the circuit conditions to any that a call originates from line 12, one of the subscribers by operating his hand gen-.

orator causes current to circulate in the line and to energize the annunciator magnet A. The fallin of the shutter indicates to the 0 orator that the line is calling, whereupon s einserts the answering plug P and by means of the key K connects her telephone set across the cord so as to ascertain the number wanted by the called subscriber. The plug P is then inserted in the jack J of the called line which we will assume to be any line equi ped with the strong generator (3. The subscriber -on the line 34 is called up by means of one of the generators G, G, etc., applied to the line through the keys K, k, k, etc. It will be noted that when either plug P or P is inserted in a line jack J or J, the corresponding annunciator A or A is disconnected in the jack, and at the same time the clearing out annunciator A becomes bridged across the connected line circuits straddling the condensers. While ringing the wanted subscriber, the key K opens the conductors 6 and 8 so that no ringing current passes back to affect thebridged annunciator, and thereafter the line and cord circuits remain intact, so that the clearing out drop is ready to respond to any magneto currents circulating therein.

l passed.

I When the subscribers have finished talking, l therefore, one or both of them may send icurrcnt from the. corresponding generator or gencrzitors over the lines, and through thc unuunciator iiiagnet il throw down i the drop. The courseof such current from the line 1-2. may be traced as follows: generator 6, 2, l, l. .3, S), .Q', 10, C, 7, P, J,

1 and back to the generator. Similarly the path for current from tlre line 34 may be traced as follows: (i 4, J, P, S, 10, 9, C, 6, P, J, 3 and back to the generator. For current through either line, it will be observed, a single condenser only is to be For current from the line P2, the condenser C is interposed in the clearline 3-4 the condenser O is inter )OSBd in the clearing out circuit. For all lost current, however, which passes -from either line to the other through the cord, both condensers C and C musthe passed through in eries, and by properly ad usting the capacage around the drop A may berednced to a negligible quantity. Upon perceiving that the shutter of the annunciator has fillcn, the operator withdraws the plug P or 1 and restores the parts to their original condition;

Fig. 2 shows a modification of the preceding circuit, in which both condensers C and C are placed in the same side of the cord circuit. I do not consider this as good an arrangementas'th other because of the tendency to unbalance the lines, but it is ract-icuble and is illustrated because it is included in the scope of my invention and therefore falls under the claims I shall make herein. f

Fig. 3 is a very condensed diagram illustrating the function of the condensers in preventing failure of the annunciator A t-o-opcrate due to a short circuit. of low resistance in one of the lines. Quite obviously, the condensers are in series for currents in the following circuit. G, l, 5, 6, 3, 4,S,C',( 7,2, G. l orcurrent going to the annunciator, however, there is only one condenser in circuit as already shown. This prevention of short-circuiting is quite as important in its way as the prevention of ringing the bells in the connected lines. For example. the short circuit shown in Fig-3 may he the branch through a l w resistance series ringer on a short individual busincss line 3-.4, while on the other band the generator G may be locatcd at one station on a long and heavily loaded country line having bridging instruments so that the amount of ringing current available for A when the last subscriber on the line is ringing is very slight. Under such circumstances, the low wound series ringer in the absence of special provision such as make will often shunt enough of the current ing out. circuit, while for current from the.

ity of these condensers, the amount of leak the low frequency ringing currents than to to make the clearing out drop inoperative. Again short circuits or crosses are not. inl're quent on country lines and upon aerial circuits in town. Such a short circuit with the shunt arrangement would absolutely prevent ringing oil. With regard to the use in harmonic ringing systems, I may state that a 16 cycle or low l'rcquency harmonic ringer is extremely sensitive andwill operate on a hand generator current throughout a large range of frequencies and with very little current so that in practice the necessity has been strongly felt for more )ositive means to overcome this defect, Obviously, the inclusion of the condensets alien-b leakage through a t short circuit is prevented. will prevent leakage through the connected ringers also and hence prevent the r operation. The condensers mav he of two in. l'. each, but are preferably of lower capacity so as to intrrduc-e ahigher resistance to the ringing current. For talking ptlrpeses, the capacity may be reduced as low as one-lourth or onelil'th in. l'. ench without detriment. 'l'he multiplied resistance ail'orded by the con-i denser-s in series together with the shunting ctleet. of the drop A itself. is sullicicnt to reduce the amount of current shuntagc so that it will neither operate the 16 cycle ringer on a connected line not injuriouslv roh the drop magnet A It should he noted particularly that any given ca iacity used in the manner I have set forth will utter a much higher impedance to the high l'requeney voice currents. 'lhtzs my arrangement has the aduintage of cutl ting down the voice currents only slightly,

and in fact imperceptibly; while for the low frequency ringing currents. which give, the most trouble, the impedance is very high. Furthermore, placing the two condensers in series for the ringing currents doubles thisincrcased impedance with respect to the hells connected in series with the same.

' Having thus described a spec-ilic embodiment of m v invention 1 may state that I am aware of various modifications that may he made in the svstetn disclosed, all of which 1 desire to include within the scope of mv claims. Thus, I may in some cases substitute non-inductive resistance [or the ('4'!)- deusers, arranged so as to have less cfl'i-ct on the talking currents than on the ringiiig currents. ()ther arrangement of the condensers may he employedmr alarger number of etmdensers may he included in the circuit. Broadly stated, the gist, of the invention lies in the )rovision of means for dill'erentinting the put s for si'rualing current and for lfliliint: current between subscribers. Merespecilicallvstatcd, it lies in the use of condensers m as to take advantage of their variation -h isfit-is. a device responsive -to such and impedance for currents ol"\'nr \in;' lrequenctes.

ent is- 1, I a signaling system, a source of signaling current, a device responsive to such signaling current, conductors for electrically m g such dcvtcc to such source of signaling ut. a second electrical path het \n h conductors, and means'locatcd o e sltlt oi the connection of such defive-m t; eonductom adapted to ot'l'er rei m o such signaling current. varying th s the frequency of such current.

2 I signaling s 'steni, a source of sigli mute). a device responsive to such gig'nnlim: current, conductors for electrically h ming such device to such source of Hgli urrent. a second electrical path bewlt conductors, andincans located in one conductor on either side of the con-' l )ltt'lic-n t such device to such conductors adapted to ot er resistance to such signaling punint aint: inversely as the frequency of such current. v

3 I a signaling system, a source of sigth -m-teuL-a device responsive to such ignaling urrent. conductors for electrically -fl g such device to such source of sigli -ut'ttttit a second electrical path hemh conductors. and menus located i mm it the conductors between such dei arch second electrical path adapted m 'f wdshitttt to such signaling current varving nuetselv as the lrequenc t' of stlch current.

-t. In a stgnuhng: system, a source of sigli meat. conductors leading from such f urieut, an electrical path between such couthtcters. a de" responsive tosnch signaling current in bridge of such conductors hetuwu such source of current andsuch -l m i l oath. and means located oneither M f ,Q hbridge for directing sutticientt u h source through such bridge to operate \ueh tie-vice regardless of the resistance otsueh electrical path.

5 I a signaling system. a stance of sigli at. eenductcrs leading from s'uch t fi ment. en elect t'ic::l path between 1 l5 signaling nu'tent in bridge of uch conductors b tuwu such source of currentand such kt i l path. undnteans located in one conductor on either side of such lz-ridge for ri i were current from'sueh source h suit} luidge to operate sucl device r gn no sextr the resistance of such e cctrical path.

6. I a agitating system, a. source of sigli at. t'xauluctors leading from such 12-5 source of (ttitklltan electrical path between d gms. a device responsive to such signalingmih'tvlti in bridge of such conducgorch s'onrceol current and such electric l ath. and means located in one of sigmiling current adapted to be connect d to the eonducteis between such devi d wit elect rival path for directing suflicient cum n from --uch source through such bridge n opt-rule such device regardle s of the resin mice f such lltiHltfi-l path. v

7. in sicuulii'ig system, a, sourceol' sir. ini current, conductors leading from sue i (it current. an electrical path between t u-h tntulminti, a device responsive to such 5 *iflfitlllng m-rentin bri ge ofs ich cozuluo t tors hetn'ecnsucl source of current and such clec'trh'iilpnih. n-nd condensers so located in the condor-lets that current flowing from 5 such source through such device will flu iln'oltuli one of such condensers endeurretn flowing: from such source through h 1 m trier-lv path will ilow through a second of srueh condensers.

8. in i1 signaling system, a. Snurcg f i h ing current, conductors leading fro h source of curzrnt, on electrical path between such eomluctors. u device responsive to such signaling: current in bridge of such co'ndno tors helween such source of current and such electrical mth. and two condensers so incutcd in tto circuits thus formed that cur rent [lowing from such source through such device will tlon' through one of such d ms and current flowing from such source through such elerlriculputh will flow through both it siltli condensers. 9. In it signaling system, t mnducwm 5 adflpilll-tt) connect tno termimil stations and an in ermediate station, a source \i such conductois at each station, a signuh receiving: derive normally connected to such conductors u! eurh stutiomundmeunsl t in such conductois for prevcntingeithoz ten minul source oi current 0 crating the mi N terminal sigimhnceiving evice i h u vontitu; the operution by either terminal I source ol cum n! of the intermediate signal 5 receiving device.

it). in 21- signs adapted to connect two terminal stations l ling system, two conductors d f intertnediute station, 21 source oi si n ling; cuncnt ndupted to be connected to su'ch u -pus at each stu-tion, a signal receiving d vice normally connectedt'o such 5i cmhhwwm at each station, and menus 1 m] in onev of such conductorson cit-Fer? ucrutmg the other termnnil id f heintermediate device for preventing igh rlninel sourceof currctnti-operotituig the ther terminal signul-reemving device, imam niingthe iipemtion by either IL in a signaling: system, two coriductois d t d to connect l ve terminal stations and an intermediate station, a source of signaling Current.:nlupted to becounected to such con- (luetors t} each station, a signal-receiving; device neinmlh' r lmected to such cc-nduc- 5 cue-h slot-ion adapted to transmit such circuiton either side in- Eiul soure of current to opcrute sue \zlli:

5 eperotingthe other terminal nit-3 1 device without nuttcrinlly lnu who terminal stations and tin intc station, a source of signaling: (urine! l in he connected to such ri iution, o signal-recoivitn onnected to such conduclnl s ml, zippnmtus at each station seal d vice w thout materially inn is voice currents in the circul M in; one termihe other terminal signal-receiving device \Hilimlt P Arm-mg the operation ol the intermediate lerice from such terminal source f rent- 12. In a combined signaling nun telephone f system, a circuit adopted it) wuneet two terminal stations and an jnlernuuluite Stilt-1011,37, source of signaling current iuluple $0 nectcd to such circuit. at ouch Hi til W Signal receiving device normally connected to such i circuit at each station, nppuratus at eeeh station adapted to transmit and receive voice currents, means in such cinnlt On each side of the intermediate devi permlt' ting either terminal so i to opera-to such intermediate S means adapted to prevent eulni rmin l ource of current operui'ingr the N l:- tninnl signal receiving derive \Hl l 111M911! ell) impeding the flow of t t fi suclicircuit between the terminal stellons.

13. In a combined signaling and telephone system, it circuit adopted to connect tn'." terminal stations and un intertuednih station, a 'ource of signalling current iuhipl to iected to such circuit at ouch station, a,

*signnl receiving device nornuilh tmmected to such circuit at each station, iit fl and receive uuiuctor of the interniediateidefv'ice for permitt g h h inter- \'oice currents, means in medote device, such menus inhtnl p either terminal source in current inn: the flow el voice current in such circuit- Such stations. 14. lnucombinedsigunlmgunn stem, two conductors udupled to connect rinedmte adapted at each 3 device normally each stated to :Lfaplltlllli and receive voice enHXt means located in one of stlilt conduct r f r telephone innung one terminal source e! current I signal-mowing eiling the flow t luxn'een the terminal source of current of the 'intorlie'cerntion ol' the intermediate dnn i mediale signoReceiving device,

welt terminal source of curn in testimony whereof I nlhx n\\ mrscnce of two witnesses i RAY it MAMON.

nature Witnesses:

Geo. A. ScoviLLE, S J. ROBERTS.

mlocated in one 65 

